Various types of measuring instruments, meters and analyzers utilize sensors to measure a variety of parameters. In one example, flue gas from combustion processes is analyzed by an oxygen analyzer to detect the presence of oxygen to give an indication of the efficiency of process heaters, oil burner systems, utility boilers, and the like. An accurate analysis can minimize fuel costs and reduce pollution while increasing safety.
Such measuring devices require periodic calibration to maintain accuracy. In some instruments, a known gas is piped in through a calibration port and the instrument is adjusted in accordance with this known reference gas. In other devices, the requirement of a reference gas may be eliminated. One such device is a General Electric OxyTrak 411 Flue Gas Oxygen Analyzer, which includes an internally calibrated sensor, the subject of U.S. Pat. No. 6,177,001, incorporated herein by this reference.
In any system, however, minimizing or eliminating costly down time for calibration is highly desirable. If, for example, a self-calibrating analyzer takes fifteen minutes to calibrate, then during that fifteen minutes, no analysis is performed and data such as the oxygen level of the flue gas is not recorded.